Ed: All I can tell you is get their manager on the line, figure out who they are subcontracting for, then tell them you will be filing a harassment complaint with the FTC against their client.
Stopping a collections call is tough stuff. The laws on what they can do all vary by state. Some places it's no more then 2 calls a day, other places it's one call every 3 hours, etc. If it's wrongful collections (in your case) then you definitely need to play hard ball with them. Call and open an FTC complain for EVERY call they place to you. Record these calls as evidence. Document them in your CDR's/etc. Then go find a hungry lawyer and tell him he can keep 80% of whatever he gets you to sue the client. I'm a big fan of the idea that stupidity should be painful.
As far as the regular telemarketer/cold-calls, they are supposed to scrub their list every 30 days. So if it's been more then a month, start telling them you are on the FTC DNC list, and that you would like to know the Company Name, thier name, and the company contact information to file an FTC Complaint. Again, record it and make records. File an FTC complaint for every call.
For cold-calls, most states don't allow you to call before 9am or after 9pm, and some allow you to call half the day on Saturday. There are also all kinds of different laws and regulations regarding state observed and federal holidays too.
